The document discusses Ruby performance profiling, highlighting issues such as slow code due to garbage collection and method calls. It covers tools for optimization, including the use of C extensions, memory profiling, and detailed system tracing methods. Recommendations include utilizing Ruby-prof, kcachegrind, and specific profiling commands for effective performance improvement.

1. Ruby performance
profiling
Minsk, SaM Solutions, 2013
Presented by Alexey Tulia
@AlexeyTulia, github.com/crible

2. Ruby. A programmer’s best friend

3. Ruby implementations

4. SLOW CODE

7. Reasons?

8. Garbage collection
Slow methods call

9. one iteration takes ~ 100ms
Garbage collection
Need one Gb?
Expect 128 GC calls!
You lose 128*0,1 = 12,8 sec
Allocated memory never returns to the system!
runs on every 8Mb of allocated memory

10. Garbage collection
More objects allocation -> more GC calls -> slow code

11. RUBY_HEAP_MIN_SLOTS=8000000
RUBY_GC_MALLOC_LIMIT=10000
Garbage collection tuning
performance patches

12. Ruby String performance
user system total real
21 chars 0.250000 0.000000 0.250000 ( 0.247459)
22 chars 0.250000 0.000000 0.250000 ( 0.246954)
23 chars 0.250000 0.000000 0.250000 ( 0.248440)
24 chars 0.480000 0.000000 0.480000 ( 0.478391)
25 chars 0.480000 0.000000 0.480000 ( 0.479662)
26 chars 0.480000 0.000000 0.480000 ( 0.481211)
27 chars 0.490000 0.000000 0.490000 ( 0.490404)

13. Ruby String performance
Heap strings
Shared strings
Embedded strings

14. struct RString {
long len;
char *ptr;
};
Ruby String performance
struct RString {
long len;
char * ptr;
VALUE shared;
};
struct RString {
char ary[RSTRING_EMBED_LEN_MAX +1];
}
RSTRING_EMBED_LEN_MAX = 23

15. Slow methods call

16. What can I do to improve performance?
Use C extensions or gems
Use plain SQL instead of frameworks
Use CPU and memory profiling
Use Rubinius or JRuby

17. THIS TALK IS
ABOUT THE TOOLS
TO FIX THE ISSUES

18. BEFOREYOU REWRITE
SH*T IN SCALA, PROFILE!

19. TOOLS FOR LINUX
LSOF
STRACE
LTRACE

20. TOOLS FOR CPU
Ruby-prof
perftools
perftools.rb

21. STRACE
trace system calls and signals
strace -cp <pid>
strace -ttTp <pid> -o <file>

22. % time seconds uses/call calls errors syscall
50,39 0,00064 0 1197 592 read
34,56 0,00044 0 609 writev
14,96 0,000019 0 1226 epoll_ctl
0,00 0,000000 0 4 close
0,00 0,000000 0 1 select
0,00 0,000000 0 4 socket
0,00 0,000000 0 4 4 connect
0,00 0,000000 0 1057 epoll_wait
100,0 0,000127 4134 596 total
strace -cp <pid>

23. LTRACE
trace dynamic library calls
ltrace -F <conf_file> -bg -x <symbol> -p pid

24. ltrace -F <conf_file> -bg -x <symbol> -p pid
-F <conf_file>
int mysql_real_query(addr,string,ulong);
void garbage_collect(void);
int memcached_set(addr,string,ulong,string,ulong);

25. ltrace -x garbage_collect
ltrace -x mysql_real_query
mysql_real_query(0x1c9e0500, "SET NAMES 'UTF8'", 16) = 0 <0.000324>
mysql_real_query(0x1c9e0500, "SET SQL_AUTO_IS_NULL=0", 22) = 0 <0.000322>
mysql_real_query(0x19c7a500, "SELECT * FROM `users`", 21) = 0 <1.206506>
mysql_real_query(0x1c9e0500, "COMMIT", 6) = 0 <0.000181>

26. RUBY-PROF
fast code profiler for Ruby

27. %self total self child calls name
------------------------------------------------------------------------
8.39 0.54 0.23 0.31 602 Array#each_index
7.30 0.41 0.20 0.21 1227 Integer#gcd
6.20 0.49 0.17 0.32 5760 Timecell#date
5.11 0.15 0.14 0.01 1 Magick::Image#to_blob
RUBY-PROF for CPU

28. KCachegrind
a tool for visualisation
http://kcachegrind.sourceforge.net

29. KCachegrind

30. KCachegrind

32. PERFTOOLS.RB
google’s performance tools for ruby code
CPUPROFILE=/tmp/myprof
pprof --calgrind ./myapp /tmp/myprof
gem install perftools.rb
RUBYOPT="-r`gem which perftools | tail -1`"
ruby my_app.rb

33. PERFTOOLS.RB
CPUPROFILE_REALTIME = 1
CPU/wall time
CPUPROFILE_OBJECTS = 1
CPUPROFILE_METHODS = 1

34. Memory profiling
GC::Profiler.report
module «objspace»
Ruby-prof

35. Out of the box in Ruby 1.9
GC::Profiler.report

36. Out of the box in Ruby 1.9
module «objspace»

37. Ruby-prof for memory
rvm install 1.9.3-p448 --patch railexpress
gem install ruby-prof
$ ruby-1.9.3-p448 test.rb
Thread ID: 14925700
Fiber ID: 17378400
Total: 3842.242188
Sort by: self_time
%self total self wait child calls name
56.94 2187.766 2187.766 0.000 0.000 20000 String#chars
32.79 1259.953 1259.953 0.000 0.000 10000 Array#join
10.17 390.812 390.812 0.000 0.000 10000 Array#shuffle
0.01 3839.391 0.336 0.000 3839.055 1 Integer#times
0.00 1562.766 0.188 0.000 1562.578 10000

38. GDB.rb
$
sudo
gdb.rb
13074
GNU
gdb
(GDB)
7.0
Reading
symbols
from
/usr/bin/ruby...done.
Attaching
to
program:
/usr/bin/ruby,
process
13074
0x00007fa8b9cb3c93
in
select
()
from
/lib/libc.so.6
(gdb)
ruby
eval
1+2
2
(gdb)
ruby
eval
Thread.list.count
17
(gdb)
ruby
objects
classes
1
YAML::Syck::Resolver
1
SystemStackError
10
OptionParser::Switch::NoArgument

39. What should I remeber before CPU profiling?
Turn GC off (GC.disable)
do_smth is so slow!!!

40. Make it work
Make it right
Make it fast

41. When should I stop performance optimisation?
Premature optimization is the root of all evil
(c) Donald Knuth

42. TOOLS MAKE
PROFILING EASIER
LEARN THEM, USE
THEM

43. Questions?
Thank you!